The present invention relates to a method of forming a magnetic substrate for an encoder scale.
Magnetic encoders having passive magnetic scales are known. Such encoders include a scale that comprises a series of markings that have a different magnetic permeability than the surrounding material. The magnetic permeability variations of the scale can be sensed using an associated readhead comprising a magnet and a plurality of magnetic field sensors (e.g. Hall sensors).
It has been described previously in JP63098501 how encoder scale marking can be formed in magnetic material by using a laser beam to heat small regions of material. These heated regions are converted from a magnetic material to a non-magnetic material.